Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of substrate or post-treatment of coated substrate
Reexamination Certificate
2000-02-15
2003-03-04
Padgett, Marianne (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of substrate or post-treatment of coated substrate
C427S539000, C427S535000
Reexamination Certificate
active
06528129
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a recording substrate having a void structure and production technique of the same. More specifically it relates to a recording medium advantageously effective to form a high quality image employing an ink jet recording system, and a production technique of the same. In more detail, the present invention relates to a technique to enhance ink image receptivity of substrate having support such as paper, plastic film, and the like by applying a discharge plasma treatment under atmospheric pressure or near atmospheric pressure to said supports.
BACKGROUND OF THE INVENTION
Ink jet systems, in a broad sense, include, for example, a bubble jet method, a piezo electrode method, and the like. Printers utilizing such systems are low in cost as well as resulting in less operating cost, compared to laser printers utilizing an electrostatic recording system. Thus, a number of ink jet printers for consumer use are being marketed and development for such printers is increasingly progressing.
As is commonly known, an ink jet system utilizes a technique in which ink is ejected from a fine opening followed by allowing the resulting ink droplets to contact a recording medium to form an image. Further, in the present invention, in describing the behavior of ink droplets which reach an image receiving surface of a recording medium and form an image, “collision”, “arrival”, and “shot” are employed to describe the same behavior. Furthermore, during ink jet printing, when image data, other than character data, are specifically printed, a recording medium is required to quickly and efficiently absorb ink droplets so that ink droplets ejected from an ink droplet ejecting unit (occasionally referred to as a printer head) are shot on the right spots and results in no blotting in the surface direction on the image receiving surface.
As recording media for such an ink jet system, plain paper is generally employed. However, with the development of better ink, ink jet printing has been applied to printing of cloth and the like. Further, along with the achievement of high quality due to finer ink droplets, multicolor, and higher quality obtained by more precise position control of the printing head, ink jet systems have recently, been applied to small volume printing with many types, small volume document printing and the like.
Currently, ink jet printers on the market are available which are capable of carrying out high resolution printing such as at least 1,200 dpi, and such type of printers not only carry out detailed printing but also can be provided with a high speed printing function.
Namely, enhancement of image quality as well as an increase in printing speed has been demanded for ink jet printers. Accordingly, research and development have been carried out not only for printers but also for the software to drive said printers, the ink, and the recording media. For example, now, in January 1999, there is a printer for consumer use, which utilizes a minimum droplet having a volume of only 6 pico liters (six trillionth liter).
At the same time, in order to allow the recording medium itself to contribute to improved image quality, exclusive printing paper has been proposed and demand for it has increased.
As described above, in the ink jet system, a method is utilized in which ink is ejected and onto a recording medium. As a result, when the recording medium is readily blotted with ink, image sharpness is degraded. On the contrary, when the recording medium exhibits low affinity with ink or repels ink, it is impossible to form images.
Special recording media which have been proposed or marketed are those in which the ink image receptivity is improved by forming a functional layer comprised of organic materials such as gelatin, PVA, and the like, or inorganic materials (silica, and the like) as the main component which is applied onto the surface of a substrate such as paper, plastic film (PET, PE, PP, PEN, and the like).
Problems to be Solved by the Invention
However, it is very difficult to control the physical surface properties such as “wettability” of the interior of voids only by coating methods. Further, quality and performance of inks are different depending on manufacturers, their products and the types of the ink itself. As a result, when compatibility is taken into account, it is difficult to determine a formula of a coating layer which works well with all types of inks. Further, it is not easy to vary the formula to suitably control the ink image receptivity.
Further, there are problems with adhesion and transfer after printing. These are due to the phenomena in which printing ink works just like an adhesive. Specifically, when printed sheets are piled up in close contact, the image receiving surface adheres with another surface. When these are forcibly peeled apart, the printed image is transferred or at the extreme case, the sheet is torn.
Further, due to the increase in printing speed, the ink ejection pitch (the time interval) has become shorter and problems with the generation of “displacement” have occurred. When an ink droplet is shot onto an image receiving layer and its soaking rate from the surface to the interior is small, as illustrated in FIGS.
13
(
a
),
13
(
b
) and
13
(
c
) an ink droplet
102
is attracted to the previously shot ink droplet
101
which has not yet soaked into the paper surface
201
, and the position of the subsequently ejected ink droplet is displaced from the intended position
104
. As a result, in the position at which an ink droplet should be present, no ink droplet is placed (no ink droplet is ejected onto the target position), and thus the color reproduction is markedly deteriorated.
Further, enhancement in the image receptivity has resulted in adverse effects. The first adverse effect is a problem with “staining”. For example, when an image receiving layer is touched with fingers, dirt as well as finger prints is attached, or the image receiving layer is subjected to swelling due to moisture absorption and the resulting image is deformed, and the like. The second adverse effect is an increase in “longitudinal blotting”. This problem occurs in such a manner that an ink droplet ejected onto the image receiving surface spreads along the surface direction and is mixed with ink droplets ejected onto adjacent positions to cause undesired color mixture.
As described above, the improvement in image receptivity is accompanied with actual problems. At present, however, effective means to solve such problems have not yet been discovered, and all firms are developing recording media employing a trial and error method. For example, in the case of a technique described in Japanese Patent Publication Open to Public Inspection No. 10-193783, a receiving layer with a compact structure is formed and a technique to allow the resulting surface to be hydrophilic is proposed. However, when only the surface is allowed to be hydrophilic, ink droplets are increasingly spread along the surface direction to degrade the quality, contrary to expectations.
Accordingly, the inventors of the present invention have investigated the problem and have revealed that an important factor is that as an ink droplet is ejected onto an image receiving surface, it is readily soaked in, in other words, the important factor is water absorbing capability (in both aspects of volume and rate) in depth of the recording medium. Specifically, it has been found that interference between ink droplets (occasionally referred to as dots) which are ejected to adjacent positions is minimized by increasing the water absorbing efficiency as well as the water absorbing rate through allowing the interior of the void structure to be hydrophilic and thus the recording function of the ink jet method can be enhanced.
Further, it has been found that contrary to making a surface hydrophilic, allowing the uppermost surface to be water-repellent is an effective measure to minimize staining on the paper surface and the like.
Further, it has been found that an ink j
Bierman, Muserlian and Lucas
Konica Corporation
Padgett Marianne
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